.\" Copyright (c) 2015 Conrad Meyer <cem@FreeBSD.org>
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.Dd August 7, 2025
.Dt CPUSET 9
.Os
.Sh NAME
.Nm cpuset(9)
\(em
.Nm CPUSET_T_INITIALIZER ,
.Nm CPUSET_FSET ,
.Nm CPU_CLR ,
.Nm CPU_COPY ,
.Nm CPU_ISSET ,
.Nm CPU_SET ,
.Nm CPU_ZERO ,
.Nm CPU_FILL ,
.Nm CPU_SETOF ,
.Nm CPU_EMPTY ,
.Nm CPU_ISFULLSET ,
.Nm CPU_FFS ,
.Nm CPU_COUNT ,
.Nm CPU_SUBSET ,
.Nm CPU_OVERLAP ,
.Nm CPU_CMP ,
.Nm CPU_OR ,
.Nm CPU_ORNOT ,
.Nm CPU_AND ,
.Nm CPU_ANDNOT ,
.Nm CPU_XOR ,
.Nm CPU_CLR_ATOMIC ,
.Nm CPU_TEST_CLR_ATOMIC ,
.Nm CPU_SET_ATOMIC ,
.Nm CPU_SET_ATOMIC_ACQ ,
.Nm CPU_TEST_SET_ATOMIC ,
.Nm CPU_AND_ATOMIC ,
.Nm CPU_OR_ATOMIC ,
.Nm CPU_COPY_STORE_REL
.Nd cpuset manipulation macros
.Sh SYNOPSIS
.In sys/_cpuset.h
.In sys/cpuset.h
.\"
.Fn CPUSET_T_INITIALIZER "ARRAY_CONTENTS"
.Vt CPUSET_FSET
.\"
.Fn CPU_CLR "size_t cpu_idx" "cpuset_t *cpuset"
.Fn CPU_COPY "cpuset_t *from" "cpuset_t *to"
.Ft bool
.Fn CPU_ISSET "size_t cpu_idx" "cpuset_t *cpuset"
.Fn CPU_SET "size_t cpu_idx" "cpuset_t *cpuset"
.Fn CPU_ZERO "cpuset_t *cpuset"
.Fn CPU_FILL "cpuset_t *cpuset"
.Fn CPU_SETOF "size_t cpu_idx" "cpuset_t *cpuset"
.Ft bool
.Fn CPU_EMPTY "cpuset_t *cpuset"
.Ft bool
.Fn CPU_ISFULLSET "cpuset_t *cpuset"
.Ft int
.Fn CPU_FFS "cpuset_t *cpuset"
.Ft int
.Fn CPU_COUNT "cpuset_t *cpuset"
.\"
.Ft bool
.Fn CPU_SUBSET "cpuset_t *haystack" "cpuset_t *needle"
.Ft bool
.Fn CPU_OVERLAP "cpuset_t *cpuset1" "cpuset_t *cpuset2"
.Ft bool
.Fn CPU_CMP "cpuset_t *cpuset1" "cpuset_t *cpuset2"
.Fn CPU_OR "cpuset_t *dst" "cpuset_t *src1" "cpuset_t *src2"
.Fn CPU_ORNOT "cpuset_t *dst" "cpuset_t *src1" "cpuset_t *src2"
.Fn CPU_AND "cpuset_t *dst" "cpuset_t *src1" "cpuset_t *src2"
.Fn CPU_ANDNOT "cpuset_t *dst" "cpuset_t *src1" "cpuset_t *src2"
.Fn CPU_XOR "cpuset_t *dst" "cpuset_t *src1" "cpuset_t *src2"
.\"
.Fn CPU_CLR_ATOMIC "size_t cpu_idx" "cpuset_t *cpuset"
.Fn CPU_TEST_CLR_ATOMIC "size_t cpu_idx" "cpuset_t *cpuset"
.Fn CPU_SET_ATOMIC "size_t cpu_idx" "cpuset_t *cpuset"
.Fn CPU_SET_ATOMIC_ACQ "size_t cpu_idx" "cpuset_t *cpuset"
.Fn CPU_TEST_SET_ATOMIC "size_t cpu_idx" "cpuset_t *cpuset"
.\"
.Fn CPU_AND_ATOMIC "cpuset_t *dst" "cpuset_t *src"
.Fn CPU_OR_ATOMIC "cpuset_t *dst" "cpuset_t *src"
.Fn CPU_COPY_STORE_REL "cpuset_t *from" "cpuset_t *to"
.Sh DESCRIPTION
The
.Nm
family of macros provide a flexible and efficient CPU set implementation,
backed by the
.Xr bitset 9
macros.
Each CPU is represented by a single bit.
The maximum number of CPUs representable by
.Vt cpuset_t
is
.Va CPU_SETSIZE .
Individual CPUs in cpusets are referenced with indices zero through
.Fa CPU_SETSIZE - 1 .
.Pp
The
.Fn CPUSET_T_INITIALIZER
macro allows one to initialize a
.Vt cpuset_t
with a compile time literal value.
.Pp
The
.Fn CPUSET_FSET
macro defines a compile time literal, usable by
.Fn CPUSET_T_INITIALIZER ,
representing a full cpuset (all CPUs present).
For examples of
.Fn CPUSET_T_INITIALIZER
and
.Fn CPUSET_FSET
usage, see the
.Sx CPUSET_T_INITIALIZER EXAMPLE
section.
.Pp
The
.Fn CPU_CLR
macro removes CPU
.Fa cpu_idx
from the cpuset pointed to by
.Fa cpuset .
The
.Fn CPU_CLR_ATOMIC
macro is identical, but the bit representing the CPU is cleared with atomic
machine instructions.
The
.Fn CPU_TEST_CLR_ATOMIC
macro atomically clears the bit representing the CPU and returns whether it
was set.
.Pp
The
.Fn CPU_COPY
macro copies the contents of the cpuset
.Fa from
to the cpuset
.Fa to .
.Fn CPU_COPY_STORE_REL
is similar, but copies component machine words from
.Fa from
and writes them to
.Fa to
with atomic store with release semantics.
(That is, if
.Fa to
is composed of multiple machine words,
.Fn CPU_COPY_STORE_REL
performs multiple individually atomic operations.)
.Pp
The
.Fn CPU_SET
macro adds CPU
.Fa cpu_idx
to the cpuset pointed to by
.Fa cpuset ,
if it is not already present.
The
.Fn CPU_SET_ATOMIC
macro is identical, but the bit representing the CPU is set with atomic
machine instructions.
The
.Fn CPU_SET_ATOMIC_ACQ
macro sets the bit representing the CPU with atomic acquire semantics.
The
.Fn CPU_TEST_SET_ATOMIC
macro atomically sets the bit representing the CPU and returns whether it was
set.
.Pp
The
.Fn CPU_ISSET
macro returns
.Dv true
if CPU
.Fa cpu_idx
is a member of the cpuset pointed to by
.Fa cpuset .
.Pp
The
.Fn CPU_ZERO
macro removes all CPUs from
.Fa cpuset .
.Pp
The
.Fn CPU_FILL
macro adds all CPUs to
.Fa cpuset .
.Pp
The
.Fn CPU_SETOF
macro removes all CPUs in
.Fa cpuset
before adding only CPU
.Fa cpu_idx .
.Pp
The
.Fn CPU_EMPTY
macro returns
.Dv true
if
.Fa cpuset
is empty.
.Pp
The
.Fn CPU_ISFULLSET
macro returns
.Dv true
if
.Fa cpuset
is full (the set of all CPUs).
.Pp
The
.Fn CPU_FFS
macro returns the 1-index of the first (lowest) CPU in
.Fa cpuset ,
or zero if
.Fa cpuset
is empty.
Like with
.Xr ffs 3 ,
to use the non-zero result of
.Fn CPU_FFS
as a
.Fa cpu_idx
index parameter to any other
.Nm
macro, you must subtract one from the result.
.Pp
The
.Fn CPU_COUNT
macro returns the total number of CPUs in
.Fa cpuset .
.Pp
The
.Fn CPU_SUBSET
macro returns
.Dv true
if
.Fa needle
is a subset of
.Fa haystack .
.Pp
The
.Fn CPU_OVERLAP
macro returns
.Dv true
if
.Fa cpuset1
and
.Fa cpuset2
have any common CPUs.
(That is, if
.Fa cpuset1
AND
.Fa cpuset2
is not the empty set.)
.Pp
The
.Fn CPU_CMP
macro returns
.Dv true
if
.Fa cpuset1
is NOT equal to
.Fa cpuset2 .
.Pp
The
.Fn CPU_OR
macro adds CPUs present in
.Fa src
to
.Fa dst .
(It is the
.Nm
equivalent of the scalar:
.Fa dst
|=
.Fa src . )
.Fn CPU_OR_ATOMIC
is similar, but sets the bits representing CPUs in the component machine words
in
.Fa dst
with atomic machine instructions.
(That is, if
.Fa dst
is composed of multiple machine words,
.Fn CPU_OR_ATOMIC
performs multiple individually atomic operations.)
.Pp
The
.Fn CPU_ORNOT
macro add CPUs not in
.Fa src
to
.Fa dst .
(It is the
.Nm
equivalent of the scalar:
.Fa dst
|=
.Fa ~ src . )
.Pp
The
.Fn CPU_AND
macro removes CPUs absent from
.Fa src
from
.Fa dst .
(It is the
.Nm
equivalent of the scalar:
.Fa dst
&=
.Fa src . )
.Fn CPU_AND_ATOMIC
is similar, with the same atomic semantics as
.Fn CPU_OR_ATOMIC .
.Pp
The
.Fn CPU_ANDNOT
macro removes CPUs in
.Fa src
from
.Fa dst .
(It is the
.Nm
equivalent of the scalar:
.Fa dst
&=
.Fa ~ src . )
.Sh CPUSET_T_INITIALIZER EXAMPLE
.Bd -literal
cpuset_t myset;

/* Initialize myset to filled (all CPUs) */
myset = CPUSET_T_INITIALIZER(CPUSET_FSET);

/* Initialize myset to only the lowest CPU */
myset = CPUSET_T_INITIALIZER(0x1);
.Ed
.Sh SEE ALSO
.Xr cpuset 1 ,
.Xr cpuset 2 ,
.Xr bitset 9
.Sh HISTORY
.In sys/cpuset.h
first appeared in
.Fx 7.1 ,
released in January 2009, and in
.Fx 8.0 ,
released in November 2009.
.Pp
This manual page first appeared in
.Fx 11.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm
macros were written by
.An Jeff Roberson Aq Mt jeff@FreeBSD.org .
This manual page was written by
.An Conrad Meyer Aq Mt cem@FreeBSD.org .
.Sh CAVEATS
Unlike every other reference to individual set members, which are zero-indexed,
.Fn CPU_FFS
returns a one-indexed result (or zero if the cpuset is empty).
